This invention relates generally to devices for filtering and separating liquids. More particularly, the present invention relates to fuel filters for removing foreign particles and separating water from fuel in the fuel supply systems of an internal combustion engine.
The absence of high standards and quality control in diesel fuel supplies dictates that an effective fuel filter be incorporated into the fuel supply system of the diesel engine. It is not uncommon for diesel fuel to have significant quantities of abrasive particles and water. The abrasive particles present the potential for permanent damage to components of the fuel injection pump. In addition, the abrasive particles can adversely effect the performance of the pump by destroying the ability of the fuel injection pump to precisely meter and deliver fuel at high pressures. The presence of water in the diesel fuel supply can cause corrosion of engine components, and during freezing conditions, can result in interruption of the fuel injection system and/or seizure of moving components.
Fuel filters commonly employ a disposable filter cartridge which is replaced at pre-established intervals of filter usage. There are a wide variety of fuel filter cartridge configurations and orientations. The replaceable cartridge is conventionally secured to the base and/or locked to the base by a locking mechanism which is releasable to allow for removal of the cartridge for replacement purposes.
In U.S. Pat. No. 5,017,285, which is assigned to the assignee of the present invention, one disclosed inverted fuel filter assembly employs a base which mounts to the vehicle and a disposable filter cartridge which is suspended directly below the filter base. The cartridge is retained to the base by a threaded collar. The collar includes a rim which retentively engages against a roll seam structure at the periphery of the cartridge housing. The collar threads to the base. The cartridge is replaced by loosening the threaded collar and dismounting the filter cartridge.
While conventional retainer devices perform in an acceptable manner, the conventional threaded locking can introduce uneven loading between different fuel filter assemblies as well as within a given fuel filter depending upon the degree of tightening or torque applied to the retainer collar. In addition, the threads are subject to exposure to various fluids and particulate matter which may seriously jeopardize the integrity and efficiency of the threaded engagement. In the field, it is often problemmatical to ascertain the proper torque or tightening technique that should be applied to properly secure the cartridge to the base. Improper loading can effect the sealing integrity of the fuel filter system and the structural integrity of the cartridge, thereby jeopardizing the effectiveness of the fuel filter and/or diminishing the useful life of the fuel filter.